bonefish+axeld:

* Removed the ref_count from vm_areas. You now always need to have the address
  space locked (read or write, depending on what you do) when dealing with
  areas.
* Added helper classes for locking the address space: AddressSpace{Read|Write}Locker,
  and MultiAddressSpaceLocker which can lock several spaces at once and makes
  sure no dead locks can happen.
* resize_area() is now using the MultiAddressSpaceLocker instead of no locking
  at all; ie. it should now be safely to use.
* Disabled transfer_area() for now; it will be changed to work like an atomic
  clone_area()/delete_area(), that is, it will hand out a new ID for the
  transfered area.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21848 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/vm_types.h

@@ -163,7 +163,6 @@ typedef struct vm_area {
 	uint32				protection;
 	uint16				wiring;
 	uint16				memory_type;
-	vint32				ref_count;
 
 	struct vm_cache		*cache;
 	vint32				no_cache_change;